Gut Bacteria, Obesity

In 1977, National Lampoon parodied Scientific American as “Scienterrific American.” I think they were on to something. I’ve written a few posts about whether we should trust scientists, whether scientists can trust each other, etc. Sadly, some scientists will publish what they are paid to publish, and some will publish whatever makes headlines, so they can continue to work. Some of their results are not reproducible, which means they aren’t really doing science. The charitable view is that eventually the scientific method will sort out the scientific from the scienterrific, but a lot of us were ingesting PFOA from Teflon long before we were told that it was a carcinogen.

Recent headlines advised that the FDA had banned sales of many antibacterial soaps, containing any of over a dozen chemicals, because “the risks outweigh the benefits.”

Studies in animals have shown that triclosan and triclocarban can disrupt the normal development of the reproductive system and metabolism, and health experts warn that their effects could be the same in humans. The chemicals were originally used by surgeons to wash their hands before operations, and their use exploded in recent years as manufacturers added them to a variety of products, including mouthwash, laundry detergent, fabrics and baby pacifiers. The Centers for Disease Control and Prevention found the chemicals in the urine of three-quarters of Americans.

That New York Times article notes that a trade group, The American Cleaning Institute, opposes the FDA ruling, and claims to have studies that support their opposition. I’m sure they do.

Finlay and Arrieta point out that while antibiotics have certainly saved many, many of us from dying young from an infectious disease, they have also changed our environment in more subtle ways. Besides the fear about developing unstoppable superbugs, we may be making ourselves susceptible to a raft of non-infectious diseases. One concern is the use of antibiotics in meat, another is the use of antibiotics in early childhood:

While these studies didn’t prove that antibiotics directly cause obesity, the consistency in these correlations, as well as those observed in livestock, prompted scientists to have a closer look. What they found was astonishing. A simple transfer of intestinal bacteria from obese mice into sterile (“germ-free”) mice made these mice obese, too! We’ve heard before that many factors lead to obesity: genetics, high-fat diets, high-carb diets, lack of exercise, etc. But bacteria—really? This raised skepticism among even the biggest fanatics in microbiology, those of us who tend to think that bacteria are the center of our world. However, these types of experiments have been repeated in several different ways and the evidence is very convincing: the presence and absence of certain bacteria early in life helps determine your weight later in life. Even more troubling is the additional research that shows that altering the bacterial communities that inhabit our bodies affects not just weight gain and obesity, but many other chronic diseases in which we previously had no clue that microbes might play a role.